Bently Nevada 3500/50-01-00 Tachometer Module

Key Parameters and Features

Core Features & Advantages

• Comprehensive Speed Monitoring: The module's standout feature is its ability to monitor multiple speed-related parameters beyond basic RPM. It measures rotor speed, speed band, peak speed, rotor acceleration, zero speed, and reverse rotation with reverse speed detection . This comprehensive monitoring enables detection of abnormal conditions such as reverse rotation or unexpected acceleration that could indicate equipment failure.

• High Accuracy and Wide Measurement Range: The 3500/50 provides exceptional measurement accuracy across its operating range. RPM accuracy is ±0.1 rpm for speeds below 100 rpm, ±1 rpm for 100 to 10,000 rpm, and ±0.01% of true shaft speed for 10,000 to 99,999 rpm . This precision is essential for overspeed protection and precise speed control applications.

• Configurable Alarm and Trip Logic: The module supports configurable Alert and Danger setpoints for each measured value, with programmable time delays from 1 to 60 seconds . When speed exceeds preset thresholds, the module triggers alarm or trip signals to prevent equipment damage from overspeed or other abnormal conditions .

• Peak Hold and Direction Detection: The module features peak hold capability, recording the highest speed, highest reverse speed, or number of reverse rotations achieved during operation, with reset functionality . This is valuable for post-event analysis and understanding transient conditions during machine startup or fault events.

• Seamless System Integration: As part of the 3500 series platform, the module integrates with System 1 software for advanced machinery diagnostics . It works alongside other 3500 monitor modules (e.g., Proximitor, Seismic, Relay modules) to provide comprehensive machinery protection .

Typical Applications

The 3500/50 Tachometer Module is widely used for speed monitoring and protection of critical rotating machinery across heavy industries:

• Turbomachinery: Steam turbines, gas turbines, and compressor trains requiring phase reference and speed validation 

• Power Generation: Generator sets, hydroelectric units, and auxiliary drive systems 

• Oil & Gas: Pumping stations, pipeline compressors, and offshore platform equipment 

• Manufacturing: High-speed spindles, paper machines, and continuous process equipment 

Frequently Asked Questions (FAQ)

Q1: What is the primary function of the 3500/50-01-00 Tachometer Module?

A: It is a dual-channel tachometer module that measures shaft rotational speed, rotor acceleration, and reverse rotation for critical rotating machinery. It compares measured values against user-programmable alarm setpoints and triggers alarm or trip signals when thresholds are exceeded .

Q2: What input types does the module support?

A: The module accepts input from both proximity probes (eddy current sensors) and magnetic pickups (magnetic speed sensors) . The input impedance is approximately 20 kΩ, and the module provides -24 VDC sensor supply at up to 40 mA per channel .

Q3: What are the key measured values provided by this module?

A: The module measures and reports: Rotor Speed, Speed Band, Peak Speed, Rotor Acceleration, Zero Speed, Reverse Rotation (including reverse speed, reverse peak speed, and number of reverse rotations), and Gap (for proximity probe inputs) .

Q4: What is the RPM accuracy of the 3500/50?

A: RPM accuracy is: ±0.1 rpm for speeds below 100 rpm; ±1 rpm for 100 to 10,000 rpm; and ±0.01% of true shaft speed for 10,000 to 99,999 rpm .

Q5: Can I configure alarm setpoints for specific measurements?

A: Yes. Alarm 1 setpoints can be set for each measured value. Alarm 2 setpoints can be set for any two of the measured values. Setpoints are configurable via software, typically from 0 to 100% of full scale, with programmable time delays from 1 to 60 seconds .

Q6: What does the "reverse rotation" function detect?

A: The reverse rotation function detects and measures backward rotation of the shaft, which can indicate a serious fault condition. It records reverse speed, reverse peak speed, and the total number of reverse rotations .

Q7: What is the difference between 3500/50 and 3500/50M?

A: The 3500/50M is the "M series" version, which offers additional channel types and enhanced measurement capabilities compared to the standard 3500/50. The 3500/50M supports the same core speed measurements with additional configurable options .

Q8: How many rack slots does the module require?

A: The monitor module occupies 1 full-height front slot, and the I/O module occupies 1 full-height rear slot (or 1 half-height rear slot for certain I/O configurations) .

Q9: What are common troubleshooting steps if the speed reading is zero?

A: Check the probe supply voltage, verify probe gap and signal wiring, confirm the shaft is actually rotating, and verify channel configuration in the 3500 software .

Q10: What maintenance is recommended for this module?

A: Recommended maintenance includes: regular inspection of probe and pickup installation; checking cables for wear or shield integrity; reviewing module status indicators; recording speed trends to identify anomalies; verifying alarm setpoints match process requirements; and checking rack connectors and I/O terminals for tightness .

Recommended Models & Related Products

The 3500/50-01-00 is part of the Bently Nevada 3500 series. Below are related models for similar or complementary monitoring needs:

Choosing the Right Model

• For standard speed monitoring applications: The 3500/50-01-00 provides comprehensive dual-channel speed, acceleration, and reverse rotation monitoring .

• For advanced measurement requirements: The 3500/50M offers additional channel types and enhanced capabilities .

• For complete machinery protection systems: Pair the tachometer module with 3500/40M or 3500/42M vibration monitors and 3500/32M relay modules for comprehensive protection .